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Hindgut digestibility in the dog (Canis familiaris) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Palmerston North, New Zealand

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Abstract

Digestibility trials are important tools used by nutritionists to establish the
nutrient requirements of an animal . The most common method used is total
faecal collection , which involves the total collection of faeces over a limited
period of time. Digestibility trials can also use indigestible markers, such as
chromium oxide and titanium oxide , which eliminate the need for a total faecal
collection and instead uses sub-sampling methods
The major aim of this thesis was to compare the suitability of chromium oxide
(Cr203) and titanium dioxide (Ti02) as indigestible markers in dogs. Due to
constraints in the study design (limited space in the facility and therefore a
requirement to house dogs in pairs), it needed to be established if Ti02
interfered with the chemical analysis of Cr203 before any animal trials were
undertaken . Different concentrations of both markers were added to freeze
dried dog faeces. The indigestible markers were then analysed for in the
laboratory and recoveries calculated . lt was established that there was no
interference of the analysis by either marker.
After a pilot study confirmed that coprophagy did not occur in the dogs, the first
study (Chapter 2) used 12 entire female Harrier hounds housed in pairs in 6
concrete floor pens. The dogs were fed twice daily with one of 4 treatment
diets; a high nutrient diet containing Cr203 or Ti02 or a low nutrient diet
containing Cr203 or Ti02. Daily intake was recorded for each dog. Each dog
received each of the 4 diets over 4 consecutive evaluation periods of 14 days
each. This study showed that 100% recovery of markers was not achieved in
the dogs. Recoveries of Cr203 were 58% and 76% respectively for high and
low nutrient diets, and recoveries of Ti02 were 80% and 74% respectively for
the same two diets . These results suggest that Ti02 is currently the best
indigestible marker for use in dogs .
Study 2 (Chapter 3) used 5 adult female Beagle dogs with surgically prepared
ileal cannulas. The ileal cannulation was conducted according to the method of
Walker et al. (1994), and the dogs were housed individually in floor pens in
temperature controlled rooms. The dogs were fed 5 commercial AAFCO
approved diets with free access to water. Dogs were randomised in a
replicated 5x 5 Latin-square design with 14 day periods , consisting of a 10 day
adaptation period and a 4 day ileal and faecal collection period. lt was found
that there were significant differences between ileal and faecal digestibility of
dry matter, crude protein, organic matter and carbohydrates of the nutrients that
we tested, indicating that there was significant metabolism of nutrients in the
hindgut of the dog .